I clock up 27,000km on my motorcycle today and finally replaced my set of tyres to Metzeler Z4. The tyre had worn down to the wear marker and is high time for replacement.
Paid S$450 for both front and rear and also replaced the inflator nozzle to the angle type for easier air inflating.

One thing baffles me is that for the past month and mostly the last week I have been experiencing lost of tyre air pressure. The last few days was very extreme, I lost 8psi, 14psi and finally 20psi of air pressure.
But when we check the tyre after removing it from the bike, I am very surprise that we cannot detect any leakage at all from the tyre, tyre walls, wheel rim and inflator nozzle valve. How and where did the air gone?

Anyway I am glad that I finally find time to replace my tyres and look forward to have a good ride.

Metzeler Z4 tyres was replaced at Southern Motors in Alexandra Village, Blk. 1006.
Job done by a mechanic call "Ah Heng", an elderly man who spoke Mandarin to me. Quite friendly but tried to sell me his own version of rear "Mud Guard" made from a recycled plastic from a Givi box and also tried to ask me to "cut out" my front fairing "Air Scoop" to improve the bike's cooling. I gave an excuse that I did not have the time and need to go home to rest.
On the whole, the mechanic workmanship was acceptable but not very good. Can return for follow up service next time but their cost seems a bit high. Maybe I should have check around for the best price instead of thrusting my friend's recommendation.